The present invention relates generally to the decoration of articles and more particularly to the decoration of articles using heat-transfer labels.
Decorating systems using heat-transfer labels have received widespread commercial use over the last several years. Typically, such decorating systems comprise a transfer mechanism for transferring a label from a continuous carrier web onto a desired article at a transfer location, a turret for sequentially positioning articles at the transfer location, a feed mechanism for sequentially positioning labels on the carrier web at the transfer location, and conveyors for feeding articles to the turret before labelling and for removing articles from the turret after labelling.
In commonly-assigned PCT Application No. PCT/US93/08191, which was published Mar. 17, 1994, and which is incorporated herein by reference, several embodiments of an apparatus for applying heat-transfer labels to containers from a carrier web are disclosed. According to a first embodiment, the apparatus is intended for applying "wrap-around" (i.e., circumferentially extending) labels to round, non-tapered containers and comprises a continuously rotating turret, a container transport system for continuously delivering containers to and away from the turret and a web transport system for moving a web containing heat-transfer labels into positioning for label transferring. The turret includes a rotatably driven shaft and a plurality of cup assemblies arranged in a circle around the shaft and coupled thereto. Each cup assembly includes a cup used to hold a container, the cup being rotatably driven independently of the shaft and in a required direction. A nozzle assembly is associated with each cup assembly and is used to secure a container within its respective cup and, if necessary, to inflate the container to impart sufficient rigidity thereto for labelling. Each cup assembly and its associated nozzle assembly together define a container holding station. The turret also includes a plurality of transfer assemblies arranged in a circle around the shaft and spaced radially inwardly from the container holder stations, each transfer assembly being associated with a corresponding container holding station. Each transfer assembly includes a heater/platen and a transfer roller. The heater/platen is mounted on a cam follower which is adapted to ride along a cam rail. The cam rail is of an appropriate length so that two or more cam followers may be riding therealong at one time. Each transfer roller is connected to its associated heater/platen in such a way that, when the cam follower is not riding along the cam rail, the transfer roller is urged radially outwardly in such a way as to transfer a label from the web onto a container.
Although decorating systems of the type described above perform reasonably well when used to apply wrap-around labels to round, non-tapered containers, such systems typically cannot be used to apply such labels to oval-shaped containers (such as those commonly used to dispense solid antiperspirant or deodorant sticks) due to a phenomenon commonly referred to in the art as "label distortion." Label distortion, the undesired stretching or shrinking of a label applied to an article, typically occurs when the surface speed of the article being decorated with a label does not match the surface speed of the carrier web supporting the label. In other words, where the surface speed of the article exceeds that of the carrier web, the label stretches when applied to the article; conversely, where the surface speed of the web exceeds that of the article, the label shrinks when applied to the article. Label distortion is not typically a problem for cylindrically-shaped articles because, when cylindrically-shaped articles are rotated at a constant angular velocity, the surface speed is also constant. By contrast, oval and other irregularly-shaped articles rotated at a constant angular velocity have significant variations in surface speed. For example, the speed of a particular point on the surface of an oval-shaped article is dependent on its distance from the axis of rotation of the article. Points further from the axis have a higher speed than points closer to the axis. Therefore, as can readily be appreciated, the speed differential can be substantial for various points along the surface of an oval-shaped article.
As a result of the above-described problem, oval-shaped containers have traditionally not been decorated with wrap-around labels, but rather, have been limited to being decorated by applying a first label of limited size to the front of the container and a second label of limited size to the back of the container. As can readily be appreciated, such small labels can be highly undesirable from an advertising or similar perspective. Moreover, the aforementioned technique typically requires the use of two turrets, the first turret being used to position the container for receipt of the first label and the second turret being used to position the container for receipt of the second label, as well as means for turning the container 180 degrees between the two turrets.
Recently, however, some decorating systems have been devised for use in applying wrap-around labels to oval-shaped containers. An example of such a system is described in U.S. Pat. No. 4,855,005, inventor Jodrey, which issued Aug. 8, 1989, and which is incorporated herein by reference. In the aforementioned patent, a decorating system is disclosed which comprises a compensated web transport arrangement in which the motion of the web is matched to that of the article being decorated. This is achieved, in accordance with one aspect of the invention, using a movable non-rotating cam and a cam follower wherein the cam follower is rigidly attached to a roller in the web transport path. The cam profile is designed to alter the speed of the web during transfer of the label to a particularly shaped article. The cam is linearly displaced by a reciprocating label shuttle bracket. The label shuttle normally accelerates the web for label transfer then decelerates the web after label transfer to permit closer spacing of labels on the carrier web. As the shuttle moves during the label transfer interval, the cam, mounted on the shuttle, displaces a roller. This roller in turn either retards or accelerates the web further so that the speed of the label receptive surface more closely approximates the speed of the web at all times during the label transfer interval.
According to a further aspect of the invention described in the aforementioned patent, the cam is designed to match a specific irregular surface. The more the shape of the article to be labelled deviates from a cylinder, the greater the web velocity correction necessary to reduce or avoid distortion. The cam profile is determined by first labelling the article by heat transfer with a pattern, normally consisting of evenly spaced vertical lines. An additional piece of the same pattern is then attached adjacent the labelled pattern so that the lines of both patterns are parallel. The distances between the correlated vertical lines of the two patterns are then measured along the boundary between patterns, perpendicular to the vertical lines. These distances indicate the amount of distortion of the label due to the web/container velocity differential at intervals on the article and are used in formulating the cam profile.
Another example of a decorating system adapted for applying wrap-around heat-transfer labels to oval-shaped containers is described in U.S. Pat. No. 4,300,974, inventor Bauer, which issued Nov. 17, 1981 and which is incorporated herein by reference. The decorating system of the aforementioned patent is adaptable to a variety of article cross-sections and is designed to ensure that the article and carrier web are moving at the same linear velocity while in contact. This is achieved by providing a cup which is connected to a rotatable cam, the article to be decorated being mounted in the cup. The article, cup and cam are all coaxially mounted, and the cam has an identical horizontal cross-section to that of the article to be labelled. The cam and the article are angularly oriented in phase synchronization. Preferably, the system includes means to preorient the article prior to depositing it in the cup. The cam contacts a cam follower, the latter being coaxially mounted with the transfer roll. The rotation of the cam is controlled by a flexible elongate member. Preferably, the flexible elongate member lies in the contact plane of the cam and cam follower. The flexible elongate member moves at the same linear velocity as the carrier web. The flexible elongate member comprises a cable.
As can readily be appreciated, the above-described systems for decorating oval and other irregularly-shaped containers are very complicated in both construction and operation, requiring the use of elaborate camming systems.
Other patents of interest include U.S. Pat. No. 3,540,968, inventor White, which issued Nov. 17, 1970, and U.S. Pat. No. 5,188,696, inventor Good, Jr., which issued Feb. 23, 1993, both of which are incorporated herein by reference.